It should be cheaper in MEX. I found out, the cheapest you get it in places, where Malaria occurs.
you really want to eat all that stuff ??? The advice you get from long term residents (foreigners) is: Mosquito net, repellent and try not to get stung. All the stuff you take in advance in most cases covers the desease - flu like symtoms - and you have a heavy fall back later. Get yourself a Emergency Kit (for remote places with no Doc around) and see a Doc if you feel really bad. They can find out in half an our whats up (blood observation by microscope).
This is my personal opinion. Talk with your Doc about it.
In eastern Africa I would take Doxicyline (has side efects but it really works) because of the cerebral Malaria, they have there. That might wipe you out in 2 days.